Ruggedized high frequency electron tube



nited States Patent O RUGGEDIZED HIGH FREQUENCY ELECTRON TUBE Dale K. Wilde, Richmond Heights, Mo., and Clifford M. Morris, Hackensack, and Kenneth E. Hanft, Carlstadt, NJ., assignors, by mesne assignments, to the United States of America as represented by the Secretary of the Army Application January 22, 1954, Serial No. 405,582

4 Claims. (Cl. 313-247) v This invention relates to electron discharge devices, and particularly to ruggedized electron discharge devices useful at ultra-high frequencies.

Electron discharge devices designed for ultra-high frequency operation are more limited as to ruggedization of structure than devices for use at lower frequencies. For example, the electrode elements in an ultra-high frequency electron discharge device must be constructed with close tolerances in spacings relative to each other and must maintain such critical spacings during operation of the devices. v

, Accordingly, it is an object of this invention to provide an improved mount structure for ultra-high frequency discharge devices of the tubular type.

A further object of this invention is to provide a new and improved ultra-high frequency discharge device having increased ruggedness. f

A still further object of this invention is to provid a new and improved ultra-high frequency discharge device wherein microphonic disturbances are reduced.

These and other objects are accomplished in accordance with this invention by providing an electron discharge device of the ultra-high frequency type which includes within an enclosure a tubular shaped cathode. Coaxially spaced around the tubular shaped cathode is a tubular shaped grid or control electrode. Coaxially disposed about the grid is a tubular anode. One end of the Agrid is connected to the walls of an aperture in a grid disk which extends transversely to the enclosure and to the electrodes. The grid disk supports this end of the grid in a firm manner. Adjacent the other end ofthe grid an insulating spacer is provided which supports the other end of the grid structure. The insulating spacer is arranged a-t a critical location to reduce to a minimum any movement of the grid with respect to the cathode and anode and therefore reduce microphonics. In one modification of 'this invention the insulating spacer is supported between two portions of the anode, while in another modica-tion of this invention the insulating spacer is supported between the anode and an exhaust tubulation.

Other aspects and advantages of the present invention will become apparent from the ensuing description in the course of which reference is had to the accompanying single sheet of drawings wherein like reference numerals refer to similar parts throughout the several views and in which:

Figures 1 and 2 are each transverse sectional views of embodiments of an ultra-high frequency electron discharge device in accordance with this invention; and

Figure. 3 is a schematic illustration of the arrangement of a grid support member designed to eliminate microphonic movement of the grid.

Referring now to Figure 1 in detail, there is shown a transverse sectional view of an ultra-high frequency electron discharge device in accordance with this in# vention. The device 10 includes opposite end sections 111, and 12 between which is mounted a grid disk 14. The disk 14 supports one end, Le. the lower end as shown in Figure l, of a grid 16 and is electrically insulated from end sections 11 and 12 by means of glass tubes 18 and 20. The grid 16 may be a wire mesh material, a cage grid, or the like. End section 11 includes a cylindrical anode assembly which comprises an elongated, hollow anode terminal member 21 having therein an inner vanode insert 22 and upper anode insert 22'. The anode assembly may be made of a metal, such as nickel, and is preferably of a size whereby a tight fit is obtained between the various parts of the anode assembly before solder 26 is applied to form a gas tight seal. Section 11 is closed at its free end by, and the device 10 is evacuated by means of, an exhaust tubulation 24. Intermediate the upper anode insert 22' and on a shoulder 25 on the inner anode insert 22, is provided an in-A sulating spacer 27 which is in contact with the control grid 16 in such a manner as to support the control grid 16 iny a firm manner. The insulating spacer 27 is rmly supported bythe friction between inner anode insert 22 and upper anode insert 22.

Section 12 of device 10 comprises a cathode assembly whichincludes a hollow tubular member 29 which serves as a cathode lead-in or terminal. Within the tubular member 29 is fixed an inner tubular support member 32 for supporting a cathode sleeve member 34 by means of a weld 33` Supported by the cathode sleeve member 34 is a cathode 37 having a coating of electron emissive material 35 thereon. The cathode 37 may press tit into the cathode sleeve member 34 as shown. Extending through the inner tubular member 32 and into the cathode 37 is a heater element 36 having legs which are connected to. lead-ins 38 which are in turn to be connected to a suitable potential source (not shown) for raising the cathode 37 to an electron emitting temperature. The lead-ins 38, for the heater element 36, are held in a fixed spaced relation by an insulating spacer disk 40 which spans the inner circumference of the inner tubular sleeve 32. When desired a getter,-not shown, may be mounted in the device and may be ashed in a conventional manner. The lead-ins 38 are sealed through a glass stem 42 which serves to close the free end of section 12 of the tube.

The seals between the various elements of discharge device 10, such as the seal between upper section 11 and the glass tube 18, may be accomplished by any of the conventional methods of forming glass-to-metal seals.

As can beseen 4from Figure l, the lower end of the control grid 16 is beveled outwardly to form a snug fit with the grid disk 14. When the grid 16 is so connected to the grid disk 14, it will be found that the lower end of the grid 16 is extremely rugged and therefore the lower end ofgrid 16 can be subjected to shock and vibrations without resulting in harmful effects to the operation of the device 10. However, prior to this invention the upper end of the grid 16 has been left unsupported so that microphonic output potentials of sizable magnitude have `occurred due to movement of this end of grid 16. When an attempt was made to support the upper end of the grid 16 by placing a support on the free end thereof it was found that the grid 16 is still conducive to microphonic action. The reason for the microphonic actionof the grid 16, even When both endsof grid 16 are supported, will be pointed out in connection with the description of Figure 3. To avoid this micro.- phonic action of grid 16 the insulating spacer 27, which snugly fits over the upper end of the grid 16, is supported approximately l/sth of the length of the grid 16 down from the upper end thereof.

. As shown in Figure 1, the upper end of the grid 16 is beveled inwardly so that the grid.16 will slide into the insulating spacer 27 and from a snug contact therewith.4 The inward lbevel' on the grid also permits a longer t Patented May 5, 1959 cathode 37 to be utilized' with a relatively short grid 1'6'since theinward extending portion of grid 16' provides an electron shield which prevents a direct electron path from the upper portion of. the cathode to the` anode. Because of the relatively short' grid 16, microphonic outputs are further reduced. The insulating spacer 27Y may' bein material such as mica or the'like.

In the embodiment of this invention shown in Figure 1 the outer circumference of the insulating spacer 27 'is supported on a shoulder 25 on the anode insert 22. This shoulder 25 may be bored in the'anode 22 as shown in Figure l with the upper anode insert' 22 iitting into the lower anode insert 22 to hold the grid insulating sup-l port member 27 in position within the device' 10,' thus resulting in a firm rugged support of the grid'16. When desired the inner surface of anode insert 22` and the outer surface of anode insert 22' may be knurled (not shown) to increase the friction between these two elements and thus insure rigid support of the insulating support member 27.

As an alternative to the structure shown in Figure l the anode assembly may be made in one single piece Cit grid is supported at both ends it has been found that the central regions of'4 ther4 grid" vibrate atI an amplitude a somewhat smaller thanwhen only one end of the grid is supported. However, the amplitude of the vibration is still substantial and microphonic outputs will still be present in the :device' Thus, if the grid is supported at both ends it has been found to provide no great advantage over the priory art type' of tube.

However, as can be seen from Figure 3, when a grid is supported in accordance with this invention, theam'plitude of the vibrational action present intermediate the support members, and between the upper support member and theY upper end of the grid is extremely small.

` After extended experimentation on this feature it has the grid has been found to produce a minimuml of microand have a ring shaped bore therein to'receivethe grid The bulb is composed of the anode terminal 21 and the inner anode insert 22', the glass tubes18'and-20; the' grid `disk 14; and the cathode terminal 29. When this is completed, the insulating spacer kis inserted through the upper bulb 11 and centered by means of a mandrel (not shown) which is inserted through the lowery end 12 and centered by means of the wall of the cathode terminal 29 and the aperture in the'grid disk 14. The upper anode insert is then pressed into position thus locking the insulating spacer in position. When these steps have been completed, the grid 16 is inserted through the lower end 12 and through the grid disk 14 and insulating spacer 27. When the grid 16 is in position it is welded to the grid disk 14. The cathode assembly is now pressed into the cathode terminal 29'. The exhaust tubulation 24 is now inserted in the upper anode insert 22 and secured there by means of solder 26. The glass stem 42, with attached getter and heater 36, is now sealed to cathode terminal 29. AThe device 10' is`now evacuated andthe exhaust tubulation 24 sealed.

Referring now to Figure 2 there is shown an embodiment of this invention wherein the anode assembly comprises =a single elongated tubular anode member 45 within an elongated hollow anode terminal member 46 and having an exhaust tube 47 adjacentone end thereof. A grid insulating support member 49 is held=into a fixed position by means of being placed between the upper end of the anode 45 and the lower endl offthe'exhaust tubulation 47. In this embodiment'acathode 50is'utilized, and therefore a grid 51, which ris longer than cathode 37 of Figure l thus permitting a larger area of electron emissive'coatingSS; As can beseen from the drawing the balance of theY tube" structure,v which` con; tains identical reference numerals for parts similar to those'shown in Fig.` l, is similar to that disclosed in connection with Figure 1 so that further' description thereofis not deemed necessary at this time.

Referring to Figure 3 there is shown al schematic rep;

resentation of the forces which have beenfoundtor cally control the location of a grid insulating support member, such as insulating support member 27 ofFig'-j Y ure" li lAs can be seenY from the drawing when only one end of the grid is supported a microphonicactiom or vibration, of the grid takesplacefthatissinilai to @pendulum action aroundr thecne supported'end of of, length L is of considerable magnitude When the phonic output potentials from movement of the grid.

Another feature of this invention, which tends toreducey the microphonic output potentials is to shorten the length ofthe grid as much as possible in accordance with the output characteristics that are desired to be reproduced by a given tube structure.

What is claimed is:

l; An ultra-high frequency electron discharge device comprising an enclosure, an apertured conductingl plate sealed transversely through the walls of saidv enclosure",4 a'l hollow elongated tubular cathode member having' an outwardly extending ilange portion sealed to said enclosure and comprising an electrode terminal end of'said enclosure, an insulating member sealed across the open end of said tubular cathode member and having leadfin wires extending therethrough, a hollow tubular cathode sleeve support member supported within said cathode member andin contact with the inner surface thereof,y a hollow cathode sleeve supported by said cathode sleeve support member, said cathode sleeve extending through the aperture in said conducting plate but spaced therefrom, an electron emissive coating in the portion of said' cathode sleeve which extends through said aperture, a` heater element within said cathode sleeve and connected to said'lead-in wires, a transverse insulating member aroundsaid lead-in wires to rigidly support said leadin wires in said device, an elongated cage type grid coaxially spaced around said electron emissive materialk of said cathode, one end of said grid being supported by'said conducting plate, a hollow tubular shaped anode member having an outwardly extending ange portion sealed to said enclosure and comprising the other elecF` trode terminal end of said enclosure, an anode insert supported by and in contact with the inner surface of saidA anode member, said anode insert being coaxiallyj spaced around said grid, an apertured insulating spacer extending from said anode linsert to said grid adjacent the other end of said grid, said grid snugly fitting into the aperture in said insulating spacer, means securing said insulating spacer within said device, and an exhaust tnbulation sealed across the open end of said device.

2. An electron discharge device as in claim l wherein' said other end of said grid bends inwardly toward said cathode sleeve'but spaced therefrom.

3. An electron discharge device as 'in claim 1 wherein said insulating spacer supports said grid at a point substantially Vs the length of said grid from said other end* of said grid.

4. An ultra-high frequency electron dischargede'vice comprising, an elongated sealed enclosure, a group of elongated electrodes including a cathode, a grid and ank anode mounted coaxially within said enclosure that order, an apertured grid disk extending transversely` through said enclosure and sealed' thereto, one end-off s'aidgrid1 being supported by said grid disk, the other endet said grid curving inwardly but spaced from said cathode, an insulating spacer supporting said grid adjacent said other end, and means including said anode engaging and supporting said insulating spacer.

References Cited in the tile of this patent UNITED STATES PATENTS Reman Iuly 6, 1915 

